Rock Paper Scissors Lizard Spock
Five actions, ten decisive pairings, and a tie-rate claim with its assumptions stated.
Rock Paper Scissors Lizard Spock is a five-action variant credited by creator Sam Kass to himself and Karen Bryla. Each action beats two, loses to two, and ties with itself. If two players choose independently and uniformly, the tie probability is 1/5 instead of the classic game’s 1/3. The Big Bang Theory included the game in season 2, episode 8.
What Is RPSLS?
Rock Paper Scissors Lizard Spock (RPSLS) adds Lizard and Spock to the classic game. On his rules page, Sam Kass credits the invention to himself and Karen Bryla. The page does not establish the exact 1998 date repeated in many summaries, so WRPSA does not state that date as fact.
With five equally likely actions, a tie occurs only when both players choose the same action: 5 matching pairs among 25 ordered pairs, or 20%. Classic RPS has 3 matching pairs among 9, or 33.3%. This comparison assumes independent, uniform choice.
The Five-Action Rule Cycle
Each action beats two others and loses to two others:
- Rock crushes Scissors, crushes Lizard
- Paper covers Rock, disproves Spock
- Scissors cuts Paper, decapitates Lizard
- Lizard poisons Spock, eats Paper
- Spock smashes Scissors, vaporizes Rock
The ten directed outcomes above are the complete ruleset. A rules table is clearer and more reliable than relying on a memorized television monologue.
Hand Gestures
- Rock: Closed fist. You know this one.
- Paper: Flat hand, palm down. Also familiar.
- Scissors: Index and middle fingers. Classic.
- Lizard: Hand forms a puppet-mouth shape, thumb underneath. Like you're making a sock puppet talk, but with your actual hand.
- Spock: The Vulcan salute. Fingers split between the middle and ring finger. If you can't do this, you may need to practice. It builds character.
What the Mathematics Changes
If both players choose independently and uniformly, each action wins 40% of rounds, loses 40%, and ties 20%. Those percentages describe a model. They do not prove that real players choose uniformly or that one action is commonly neglected.
Five possible actions create more opponent frequencies to estimate, so useful tendency claims require more observations. No reviewed source establishes a universal Spock preference, Lizard avoidance, or predictable beginner pattern.
The Big Bang Theory Appearance
The Big Bang Theory included the game in season 2, episode 8, “The Lizard-Spock Expansion.” The official show channel publishes a clip of the scene. That documents the appearance; it does not by itself measure how many people learned or played the variant because of it.
Kass’s own rules page says he created the game with Karen Bryla and describes repeated ties with a familiar opponent as the motivation. WRPSA treats that page as the attribution source and does not turn the creator’s personal estimate into a population statistic.
Can an Event Use RPSLS?
WRPSA’s published competitive rules cover the classic three-gesture game. An organizer may run RPSLS only by declaring that separate ruleset before play and labeling its records accordingly. The hosting tools and event formats should never mix five-action results into classic standings without an explicit ruleset identifier.
Related Rule Variations
RPSLS is one documented way to extend the classic cycle. The RPS variations guide explains which balance and tie-rate claims can be derived mathematically and which historical claims need sources.